Its always helpful when you ask a question, and people answer with everything but something relevant to the thing you asked in the first place!

Who knows, maybe you've already found out more, since this post seems a little old.. But, in case you haven't - yes, it is more than just a tower defense game with loot. Tower defense is definitely part of it, and you will need to do some strategical tower placing and all of the standard things that go with it. But, there is a variety of classes you can choose for your character to be, each of which can be built differently on a talent system, that will make huge differences in your experience. You can play both offense and defense. Besides all of the main maps, which mostly follow the formula of 'defend 1, 2, 3, or 4 crystals from enemies', there is also a variety of other challenge modes you can play. You can play multiplayer in the game as a whole, and you can also play a PVP Capture the Flag style game. Everything you can do can be set to varying levels of difficulty, from Easy to Insane and the new Nightmare. I think the thing that really separates it from your average TD game, though, is the multiplayer - its a feature you can't really get the most out of the game without trying.